Definition of thriftless in English:

adjective

A certain disillusion is perhaps necessary for the practice of conversation: it is the art of the thriftless genius, appropriate to the brilliant failure, the genius manqué, and the inebriate.

The U.S. Congressional Record quotes an unnamed speaker as saying ‘an idle and thriftless race of savages cannot be permitted to stand guard at the treasure vaults of the nation which hold our gold and silver.’

Yet, as Smiles observed, ‘No laws, however stringent, can make the idle industrious, the thriftless provident, or the drunken sober.’

Derivatives

thriftlessly

I've been thriftlessly spending on clothes and the like that I don't see a stop to it any time soon, though I am making myself small promises.

Reutoff suburb is the wellspring of inspiration that is thriftlessly used by the musicians for the creation of deep, psychedelic and highly forcible music implementing the inaccessible secret of Russian spirit.

Roy Marshall felt that cricket contained two kinds of madman: the fast bowler, because he expended his energies so wildly and thriftlessly; but also the opening batsman.